Construction method of immersed tube pre-embedded connection channel

Abstract

A construction method of an immersed tube pre-embedded connection channel comprises the steps that a pre-embedded space is excavated on the earth surface between two preset excavation tunnels, a connection channel prefabricated part is placed in the pre-embedded space, cement mortar is poured, backfilling and compacting are conducted, and then excavation of the tunnels on the two sides is conducted; after tunnel construction is completed, emergency protection doors are installed at the positions corresponding to the two sides of the connecting channel prefabricated part in the length direction, cement mortar poured in the previous step enables the connecting channel prefabricated part and the tunnel to form an integral structure with better waterproof performance, and then excavation is conducted from the positions of the emergency protection doors in the tunnel; and the two ends of the connecting channel prefabricated part are broken through, and construction of the immersed tube pre-embedded connecting channel is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of the construction of connecting channels in subway stations, and more specifically to a construction method for a connecting channel with pre-buried immersed tubes. Background Art

[0002] A connecting channel is a horizontal passageway set between two subway tunnels. By connecting the two tunnels, it can play roles such as safely evacuating passengers, draining water from the tunnels, and providing fire prevention and firefighting functions. It is the lifeline in case of accidents in the tunnels. The construction of existing connecting channels mostly takes place after the completion of the two tunnels, with excavation construction carried out separately in the two tunnels, generally using the freezing method or the mechanical method. The overall construction time is long, the cost is high, the risk is large, the construction period is slow, and the construction space inside the tunnels is limited, which is not conducive to the use of large-scale construction machinery during the construction process. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method for a connecting channel with pre-buried immersed tubes. By excavating a pre-buried space on the ground between the two tunnels and placing prefabricated components of the connecting channel, and then connecting the two ends of the prefabricated components to the tunnels after the subsequent tunnel excavation, the problems in the prior art are solved.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a method for constructing a immersed tube pre-buried communication channel, comprising the following steps: ① on the surface between two preset excavated tunnels, a pre-buried space is excavated downwards using a troughing machine or a rotary drilling rig, and both sides of the pre-buried space in the length direction are overlapped with the tunnels to be excavated; ② after the excavation of the pre-buried space in step ① is completed, a layer of concrete is poured into the bottom position of the pre-buried space, and cured to form a hard platform; ③ after the curing of the hard platform in step ② is completed, a crane is used to place the communication channel prefabricated component on the hard platform in the pre-buried space, and an appropriate distance is left between the two ends of the communication channel prefabricated component in the length direction and the tunnels to be excavated according to the hydrogeological conditions, and cement mortar is poured on the periphery of the communication channel prefabricated component, wherein the communication channel The prefabricated part is a concrete prefabricated part that is closed on all sides and hollow inside; ④ After the connection channel prefabricated part in step ③ is placed and the cement mortar is poured, backfill the earth into the embedded space and perform compaction operation; ⑤ After the backfilling of earth in step ④ is completed, the excavation and support of the tunnels on both sides and the installation of the internal segments are carried out according to the set position; ⑥ After the installation of the tunnel segments in step ⑤ is completed, emergency protection doors are installed on the segments corresponding to the positions at both ends of the length direction of the connection channel prefabricated part; ⑦ After the installation of the emergency protection doors in step ⑥ is completed, excavate in the tunnels on both sides to the position of the connection channel prefabricated part; ⑧ When the excavation reaches the end position of the connection channel prefabricated part in step ⑦, the closed ends of the connection channel prefabricated part in the length direction are broken and opened, and the two tunnels are connected to complete the construction of the immersed tube pre-buried connection channel. The connection channel prefabricated part includes a bottom plate, vertical plates on both sides, an arc plate on the top, and a sealing plate at the end, wherein the bottom plate, the vertical plate, and the arc plate are all provided with steel cages. The spacing between the communication channel prefabricated parts and the tunnel segments on both sides is 40-50cm. The concrete thickness of the communication channel prefabricated parts is 30-40cm, and the diameter of the internal hollow is 200-300cm. The outer periphery of the communication channel prefabricated parts is provided with embedded connecting bars. The height of the poured cement mortar in step ③ exceeds the height of the communication channel prefabricated parts by 80-100cm. When pouring concrete to form a hard platform in step ②, anti-seepage agent and quick-setting agent are added to the concrete to improve its strength and anti-seepage performance. When backfilling the earth in step ④, the method of layered backfilling and layer-by-layer compaction is adopted. The thickness of each layer after compaction does not exceed 30cm to ensure the density and stability of the backfill soil. When digging the communication channel in step ⑦, a combination of manual and mechanical methods is adopted. First, a small excavator is used for preliminary excavation, and when approaching the communication channel prefabricated parts, manual fine excavation is switched to protect the prefabricated parts from damage. When breaking and opening the closed ends of the prefabricated parts of the communication channel in step ⑧, static blasting technology is used to reduce the vibration impact on the surrounding soil and tunnel, ensuring construction safety and tunnel stability.

[0005] The positive effects of the present invention are as follows: For a construction method of a pre-buried immersed connecting passage according to the present invention, a pre-buried space is first excavated on the ground surface between two preset excavation tunnels, and a precast connecting passage component is placed in the pre-buried space. After pouring cement mortar and backfilling and compacting, excavation of the two side tunnels is carried out. After the tunnel construction is completed, emergency protection doors are installed at the positions corresponding to both sides in the length direction of the precast connecting passage component. The cement mortar poured in the previous steps forms an integral structure with better waterproof performance between the precast connecting passage component and the tunnel. Then, excavation is carried out from the position of the emergency protection door inside the tunnel, and both ends of the precast connecting passage component are opened to complete the construction of the pre-buried immersed connecting passage. Compared with the traditional construction method, the pre-buried precast connecting passage component is carried out in advance before tunnel excavation, without the need for through-connection excavation construction at the corresponding positions of the two tunnels, effectively reducing the labor intensity, shortening the construction time required, significantly reducing the cost, significantly reducing the risk, and significantly shortening the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of the state after step ① of the present invention is completed; Figure 2 is a schematic diagram of the state after step ② of the present invention is completed; Figure 3 is a schematic diagram of the state after step ③ of the present invention is completed; Figure 4 is a schematic diagram of the state after step ④ of the present invention is completed; Figure 5 is a schematic diagram of the state after step ⑤ of the present invention is completed; Figure 6 is a schematic diagram of the state after step ⑥ of the present invention is completed; Figure 7 is a schematic diagram of the state after step ⑦ of the present invention is completed; Figure 8 is a schematic diagram of the state after step ⑧ of the present invention is completed; Figure 9 is a schematic diagram of the structure of the precast connecting passage component. DETAILED DESCRIPTION OF THE INVENTION

[0007] A construction method of a pre-buried immersed connecting passage according to the present invention, as Figures 1-7 shown, includes the following steps: ① On the ground surface between two preset excavation tunnels, use a grooving machine or a rotary drilling rig to excavate a pre-buried space 1 downward. Both sides in the length direction of the pre-buried space 1 overlap with the tunnels to be excavated; ② After the excavation of the pre-buried space 1 in step ① is completed, pour a layer of concrete at the bottom layer in the pre-buried space 1 and cure it to form a hard platform 3; ③After the hard platform 3 in step ② is cured, use a crane to place the precast segment 2 of the connecting passage on the hard platform 3 in the embedded space 1. Leave an appropriate distance between the two ends of the precast segment 2 of the connecting passage in the length direction and the tunnel to be excavated according to the hydrogeological conditions, and pour cement mortar around the precast segment 2 of the connecting passage. The precast segment 2 of the connecting passage is a concrete precast member with a closed perimeter and a hollow interior, and the specific dimensions of the concrete precast member are precast according to the design space requirements; ④After the precast segment 2 of the connecting passage in step ③ is placed and the cement mortar is poured, backfill the soil in the embedded space 1 and perform a compaction operation; ⑤After the soil backfilling in step ④ is completed, carry out the excavation support of the two tunnels on both sides and the installation of the internal segment according to the set positions; ⑥After the segment installation of the tunnel in step ⑤ is completed, install emergency protection doors 4 on the segments corresponding to both ends of the precast segment 2 of the connecting passage in the length direction; ⑦After the emergency protection doors 4 in step ⑥ are installed, excavate towards the position of the precast segment 2 of the connecting passage in the two tunnels on both sides; ⑧When the excavation in step ⑦ reaches the end position of the precast segment 2 of the connecting passage, break through the closed ends at both ends of the precast segment 2 of the connecting passage in the length direction to connect the two tunnels and complete the construction of the immersed tube embedded connecting passage.

[0008] The above construction method is to excavate downward and embed the precast segment 2 of the connecting passage on the ground surface between the preset excavations of the two tunnels before the tunnel excavation, and then connect the precast segment 2 of the connecting passage with the tunnels on both sides after the tunnel is built. Compared with the traditional method of excavating and connecting between the two tunnels after the tunnel is built, there is no need to carry out through-connection excavation construction at the corresponding positions of the two tunnels, effectively reducing the labor intensity, and the construction time required is shorter, the cost is greatly reduced, the risk is significantly reduced, and the construction period is significantly shortened.

[0009] Step ① is to use existing excavation equipment, such as a grooving machine or a rotary drilling rig, to excavate the embedded space 1 of the connecting passage downward on the ground surface between the preset excavations of the two tunnels, and make the excavated embedded space 1 overlap with the positions of the two tunnels to be excavated on both sides. It is convenient to carry out the construction of various mechanical equipment above the ground surface, not affected by the space of traditional tunnel operations, and overlaps with the spaces reserved on both sides of the tunnel. It can not only form a better waterproof overall structure between the subsequent placed precast segment 2 of the connecting passage and the tunnel, but also does not affect the subsequent tunnel excavation construction.

[0010] In Step ② and Step ③, a layer of concrete is poured at the bottom position within the embedded space 1, cured to form a rigid platform 3, and a precast segment of the connection passage 2 is placed on the rigid platform 3. Appropriate distances are left between the two ends of the precast segment of the connection passage 2 in the length direction and the tunnels to be excavated according to the hydrogeological conditions, and cement mortar is poured to position and install the precast segment within the embedded space 1. Meanwhile, a waterproof structure between the precast segment and the tunnels can be formed. The rigid platform 3 and the cement mortar poured on the periphery can form an integral waterproof structure, effectively preventing water ingress and other situations during the subsequent operation of connecting the tunnels and the precast segment, with higher waterproof safety performance. The appropriate distances are determined according to the formation, hydrogeological conditions, and burial depth, which can achieve waterproof performance without affecting the normal construction of the subsequent tunnels and the normal progress of the connection operation.

[0011] Different from the traditional method of excavating a space between two tunnels and casting and constructing the connection passage on-site, mass-producing the connection passage as pre-embedded parts and pre-embedding them in advance before tunnel excavation can greatly reduce the construction difficulty and effectively improve the overall construction efficiency. Several groups of precast segments of the connection passage 2 can be pre-embedded between two tunnels in advance. After the tunnel construction is completed, the tunnels and the precast segments of the connection passage 2 can be connected one by one.

[0012] In Step ④, after the precast segment of the connection passage 2 is installed, the embedded space 1 is backfilled with soil and compacted to restore the initial surface state and allow the construction of auxiliary buildings of the subway facilities on it. Meanwhile, it also facilitates the subsequent excavation and construction of the subway tunnels. In Step ⑤, after the soil backfilling is completed, normal excavation support of the two tunnels on both sides and the laying and installation of internal segments are carried out.

[0013] After the tunnels are built, it is necessary to connect the two tunnels on both sides with the precast segment of the connection passage 2. Since the cement mortar poured initially fills the space between the precast segment of the connection passage 2 and the two tunnels on both sides, forming an integral structure with better waterproof performance and realizing the pre-connection between the precast segment of the connection passage 2 and the tunnel segments, groundwater can be prevented from entering the tunnels during the subsequent excavation process. To ensure the safety during the construction process, emergency protection doors 4 are installed on the segments corresponding to the two ends of the precast segment of the connection passage 2 in the length direction.

[0014] There are two steps in the excavation process. One is to excavate the part of the cement mortar filled between the tunnel segment and the precast piece 2 of the connection passage. The other is to break through the closed ends at both ends of the precast piece 2 of the connection passage in the length direction, so as to realize the connection and penetration of the connection passage between two pairs of tunnels. The above construction is steps ⑦ and ⑧, and thus the construction of the immersed tube embedded connection passage is completed. After the connection passage is penetrated, if there is a danger in the tunnel, the installed emergency protection door 4 can be opened in time to allow the internal personnel to transfer to another tunnel for refuge. Among them, the emergency protection door 4 is in the normally open state. When there is a danger in one side of the tunnel, the internal passengers can enter the relatively safe tunnel on the other side through the connection passage. After the personnel transfer is completed, the emergency protection door 4 is closed to prevent harmful gases, smoke or water inrush from entering the relatively safe tunnel.

[0015] Further, as Figure 8 shown, the precast piece 2 of the connection passage includes a bottom plate 5, vertical plates 6 on both sides, an arc plate 7 at the top, and a sealing plate 8 at the end. The above bottom plate 5, vertical plates 6, arc plate 7 and sealing plate 8 form a sealed space. To improve the strength of the precast piece, a steel reinforcement cage 9 is provided inside the bottom plate 5, vertical plates 6 and arc plate 7. In the subsequent excavation and breakthrough operation, the sealing plate 8 needs to be damaged, and there is no need to additionally set a steel reinforcement cage 9 inside it, which can not only facilitate the breaking operation but also reduce the production cost.

[0016] Further, in order to reserve enough deviation distance for the subsequent shield propulsion of the tunnel excavation after the precast piece 2 of the connection passage is installed, the distance between the precast piece 2 of the connection passage and the tunnel segments on both sides is 40 - 50 cm.

[0017] Further, in order to improve the overall strength of the precast piece 2 of the connection passage and reserve enough escape space inside, the concrete thickness of the precast piece 2 of the connection passage is 30 - 40 cm, and the diameter of the internal hollow part is 200 - 300 cm.

[0018] Further, the outer periphery of the precast piece 2 of the connection passage is provided with embedded connecting bars 10. The setting of the embedded connecting bars 10 can make the precast piece 2 of the connection passage form a more compact integral structure with the concrete poured in the subsequent embedded space 1, and make the precast piece 2 of the connection passage be stably positioned in the embedded space 1 to realize the embedded positioning installation at the set position.

[0019] Further, in step ③, the height of the poured cement mortar exceeds the height of the precast piece 2 of the connection passage by 80 - 100 cm, which can not only ensure the positioning installation of the precast piece 2 of the connection passage in the embedded space 1 and form a waterproof integral structure with the overlapping tunnel, but also does not affect the subsequent excavation of the tunnel.

[0020] The thickness of the hard platform 3 can be about 50-60 cm. When pouring cement mortar, it can be poured thicker at the end position of the connecting channel prefabricated part 2, and then it can be opened later. The subsequently built tunnel is tangent to the overlap of the poured cement mortar, has better waterproof performance, and the safety performance in the subsequent opening operation is higher.

[0021] The emergency protection door 4 is installed in the tunnel before the tunnel opening operation, so as to avoid water leakage into the tunnel during the subsequent excavation and opening operation. During the excavation of the embedded space 1, the auxiliary method of mud wall protection can be adopted to avoid the collapse of the side wall of the embedded space 1, and a counterweight block can be added to the communication channel prefabricated member 2 to facilitate the smooth lowering of the communication channel prefabricated member 2 in the mud.

[0022] Furthermore, when pouring concrete to form the hard platform 3 in step ②, an anti-seepage agent and an accelerating setting agent are added to the concrete to improve its strength and anti-seepage performance.

[0023] Furthermore, when backfilling the soil in step ④, a layered backfilling and layer-by-layer compaction method is adopted, and the thickness of each layer after compaction does not exceed 30 cm, so as to ensure the density and stability of the backfill soil.

[0024] Furthermore, when digging the communication channel in step ⑦, a combination of manual and mechanical methods is adopted, and a small excavator is used for preliminary digging first, and then manual fine digging is used when approaching the communication channel prefabricated part 2 to protect the prefabricated part from damage.

[0025] Furthermore, when breaking and opening the closed ends of the communication channel prefabricated member 2 in step ⑧, static blasting technology is used to reduce the vibration impact on the surrounding soil and the tunnel, thereby ensuring construction safety and tunnel stability.

[0026] The technical solution of the present invention is not limited to the scope of the embodiments described in the present invention. The technical contents not described in detail in the present invention are all well-known technologies.

Claims

1. A method for constructing a immersed tube pre-buried communication channel, characterized in that: The method comprises the following steps: ① using a trenching machine or a rotary drilling rig to dig a pre-buried space (1) downward on the ground surface between two preset excavated tunnels, wherein both sides of the pre-buried space (1) in the length direction overlap with the tunnels to be excavated; ② After the pre-buried space (1) in step ① is excavated, a layer of concrete is poured into the bottom layer of the pre-buried space (1), and cured to form a hard platform (3); ③ After the hard platform (3) in step ② is maintained, a crane is used to place the communication channel prefabricated component (2) on the hard platform (3) in the pre-buried space (1), and an appropriate distance is left between the two ends of the communication channel prefabricated component (2) in the length direction and the tunnel to be excavated according to the hydrogeological conditions, and cement mortar is poured around the periphery of the communication channel prefabricated component (2), wherein the communication channel prefabricated component (2) is a concrete prefabricated component that is closed on all sides and hollow inside; ④ After the connection channel prefabricated parts (2) in step ③ are placed and the cement mortar is poured, backfill the pre-buried space (1) with earth and perform compaction operations; ⑤ After the backfilling of earthwork in step ④ is completed, excavation and support of the tunnels on both sides and installation of internal segments are carried out according to the set positions; ⑥ After the tunnel segments in step ⑤ are installed, emergency protection doors (4) are installed on the segments corresponding to the two ends of the length direction of the connecting channel prefabricated component (2); ⑦ After the emergency protection door (4) in step ⑥ is installed, dig towards the location of the prefabricated part (2) of the connecting channel in the tunnels on both sides; ⑧ When the excavation in step ⑦ reaches the end position of the connecting channel prefabricated component (2), the closed ends of the connecting channel prefabricated component (2) in the length direction are broken and opened to connect the two tunnels, thereby completing the construction of the immersed tube pre-buried connecting channel.

2. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: The communication channel prefabricated component (2) comprises a bottom plate (5), vertical plates (6) on both sides, an arc plate (7) on the top, and a sealing plate (8) at the end, wherein a steel cage (9) is provided inside the bottom plate (5), the vertical plates (6), and the arc plate (7).

3. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: The distance between the connecting channel prefabricated part (2) and the tunnel segments on both sides is 40-50 cm.

4. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: The concrete thickness of the communication channel prefabricated component (2) is 30-40 cm, and the diameter of the inner hollow is 200-300 cm.

5. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: The outer periphery of the communication channel prefabricated component (2) is provided with pre-embedded connecting ribs (10).

6. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: In step ③, the height of the cement mortar poured exceeds the height of the connecting channel prefabricated part (2) by 80-100 cm.

7. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: When pouring concrete to form the hard platform (3) in step ②, an anti-seepage agent and an accelerating setting agent are added to the concrete to improve its strength and anti-seepage performance.

8. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: When backfilling the soil in step ④, adopt the method of layered backfilling and layer-by-layer compaction. The thickness of each layer after compaction shall not exceed 30cm to ensure the density and stability of the backfill soil.

9. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: When digging the communication channel in step ⑦, a combination of manual and mechanical methods is used. A small excavator is used for preliminary digging first, and then manual fine digging is used when approaching the communication channel prefabricated part (2) to protect the prefabricated part from damage.

10. The method for constructing a immersed tube pre-buried communication channel according to claim 1, characterized in that: When breaking and opening the closed ends of the communication channel prefabricated member (2) in step ⑧, static blasting technology is used to reduce the vibration impact on the surrounding soil and the tunnel, thereby ensuring construction safety and tunnel stability.

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